The present invention relates to a system for controlling enquiry of a database for use in a computer system and, in particular, to a system for making an efficient enquiry both of a relational type database and a network type data base built on a network.
The control of the enquiry of the network type database, unlike that of the relational type database, is arranged so that a single enquiry is made by processing a single record and, in order to realize an enquiry of a file which is the entire set of records, as in the enquiry control of the relational type database, it is necessary to combine a plurality of enquiries.
FIGS. 1 and 2 illustrate a conventional relational type database enquiry control system and a conventional system for controlling enquiry of the network-type database, respectively, in which a database enquiry statement which is entered from a terminal unit 1 or application program 2 is analyzed for its content by a relational type database control portion 20 or network type database control portion 30. In the former (relational type database 6), the relational type database control portion 20 retrieves the file (set of records) of the relational type database 6. From that, the user selects and emits a desired record. IF1 through IF6 each illustrate an interface.
In the foregoing database enquiry control system, when the records are retrieved by the network type database 14, unlike the relational type data base 6, the user must enquire once for each record.
Therefore, in such a system, in order to achieve the inquiries equivalent to a single enquiry statement of the relational type database by the control of the network type database enquiry, it is necessary to combine a plurality of enquiry statements, which causes the productive efficiency to be reduced as compared with the relational type database.
In view of such circumstances, the present invention was made and, its object is to provide an enquiry control system which is improved so that the enquiry control for the network-type database can be achieved as if it were carried out in the relational type database.